Deposition apparatus and use methods

ABSTRACT

A deposition apparatus comprises: an infeed chamber; a preheat chamber; a deposition chamber; and optionally at least one of a cooldown chamber and an outlet chamber. At least a first of the preheat chamber and the cooldown chamber contains a buffer system for buffering workpieces respectively passing to or from the deposition chamber.

CROSS-REFERENCE TO RELATED APPLICATION

Benefit is claimed of U.S. Patent Application No. 62/011,103, filed Jun.12, 2014, and entitled “Deposition Apparatus and Use Methods”, thedisclosure of which is incorporated by reference herein in its entiretyas if set forth at length.

BACKGROUND

The disclosure relates to aerospace coatings. More particularly, thedisclosure relates to vapor deposition systems.

Exemplary coating apparatus are shown in United States PatentApplication Publication 20120282402A1 of Neal et al. published Nov. 8,2012 and entitled “Coating Methods and Apparatus” and United StatesPatent Application Publication 20120196030A1 of Neal et al. publishedAug. 2, 2012 and entitled “Coating Methods and Apparatus”. A low vacuumoperation (LVO) apparatus is disclosed in International ApplicationPCT/US14/28489 of Brian T. Hazel et al., filed Mar. 14, 2014 andentitled “Deposition Apparatus and Methods”.

SUMMARY

One aspect of the disclosure involves a deposition apparatus comprising:an infeed chamber a preheat chamber; a deposition chamber; andoptionally at least one of a cooldown chamber and an outlet chamber. Atleast a first of the preheat chamber and the cooldown chamber contains abuffer system for buffering workpieces respectively passing to or fromthe deposition chamber.

A further embodiment may additionally and/or alternatively include aworkpiece flowpath entering the infeed chamber and proceedingsequentially through the preheat chamber, the deposition chamber, thecooldown chamber, and then exiting the outlet chamber.

A further embodiment may additionally and/or alternatively include thepreheat chamber being a combined preheat/cooldown chamber.

A further embodiment may additionally and/or alternatively includewithin the preheat/cooldown chamber, a workpiece flowpath having aninfeed leg and an outfeed leg coincident at endpoints.

A further embodiment may additionally and/or alternatively include: theinfeed chamber being a combined infeed/outlet chamber; the preheatchamber being a combined preheat/cooldown chamber; and a workpieceflowpath entering the infeed/outlet chamber and proceeding sequentiallythrough the preheat/cooldown chamber, the deposition chamber, thepreheat/cooldown chamber again, and then exiting the infeed/outletchamber.

A further embodiment may additionally and/or alternatively include thebuffer system comprising a conveyor having a plurality of receptacles.

A further embodiment may additionally and/or alternatively include theconveyor being a continuous loop circuit.

A further embodiment may additionally and/or alternatively include thebuffer system comprising, along a workpiece flowpath from said infeedchamber to said outlet chamber: a first transfer mechanism positioned inthe first chamber to transfer workpieces to said first chamber and asecond transfer mechanism positioned in the first chamber to transferworkpieces from the first chamber.

A further embodiment may additionally and/or alternatively include thefirst transfer mechanism and the second transfer mechanism eachcomprising an arm mounted to be rotationally driven about an axis andtranslated parallel to said axis.

A further embodiment may additionally and/or alternatively include thebuffer system comprising, along a workpiece flowpath: a first transfermechanism positioned in the first chamber to transfer workpieces to saidfirst chamber; a second transfer mechanism positioned in the firstchamber to transfer workpieces from the first chamber; and anintermediate transfer mechanism positioned in the first chamber to shiftthe workpieces between a plurality of receptacles.

A further embodiment may additionally and/or alternatively include theplurality of receptacles including: a first receptacle accessible by thefirst transfer mechanism but not the second transfer mechanism; and asecond receptacle accessible by the second transfer mechanism but notthe first transfer mechanism.

A further embodiment may additionally and/or alternatively include theplurality of receptacles further including at least a third receptacleaccessible by neither the first transfer mechanism nor the secondtransfer mechanism.

A further embodiment may additionally and/or alternatively include aworkpiece flowpath from said infeed chamber to said outlet chambercomprising: a first leg from the infeed chamber to the depositionchamber; and a second leg from the deposition chamber to the outletchamber, essentially parallel but opposite to the first leg.

A further embodiment may additionally and/or alternatively include thedeposition chamber comprising: an electron beam gun; and an ingot.

A further embodiment may additionally and/or alternatively include thedeposition chamber comprising a workpiece handler having a range ofmotion including: a first condition for receiving a workpiecetransferred from the preheat chamber; and a second condition for handingoff the workpiece for transfer to the cooldown chamber

A further embodiment may additionally and/or alternatively include theworkpiece handler range of motion including one or more depositionconditions accessible via rotation about a first axis relative to thefirst condition and second condition.

A further embodiment may additionally and/or alternatively include theone or more deposition conditions comprising: a first depositioncondition for deposition from a first plume of a first material; and asecond deposition condition for deposition from a second plume of asecond material, said second deposition characterized by a shiftparallel to the first axis relative to the first deposition condition.

A further embodiment may additionally and/or alternatively include theworkpiece handler range of motion between said first condition and saidsecond condition comprising a translation parallel to the first axis.

A further embodiment may additionally and/or alternatively include theworkpiece handler range of motion including a part continuous rotationdegree of freedom about an axis orthogonal to the first axis.

A further embodiment may additionally and/or alternatively include: aworkpiece handler positioned to hold workpieces for coating in thedeposition chamber; a transfer mechanism positioned to transferworkpieces between at least two of the chambers; a plurality of partholders, each having: a first feature complementary to an engagementfeature of the workpiece handler; and a second feature complementary toan engagement feature of the transfer mechanism.

A further embodiment may additionally and/or alternatively include thefirst engagement feature comprising a tapered feature tapering toward aproximal end and the second engagement feature comprising a channel.

A further embodiment may additionally and/or alternatively include: thepart holders each having an axis; the channel being open radiallyoutward from the axis; and the tapered feature being centered along theaxis.

A further embodiment may additionally and/or alternatively include amethod for using the deposition apparatus to coat a plurality ofworkpieces. The method comprises: opening an inlet port of the infeedchamber; inserting one or more of the workpieces to the infeed chamberthrough its inlet port; closing the infeed chamber inlet port; pumpingdown the infeed chamber; opening a first transfer port between theinfeed chamber and the preheat chamber; transferring the one or moreworkpieces through the first transfer port to the preheat chamber;heating the one or more workpieces in the preheat chamber; opening asecond transfer port between the preheat chamber and the depositionchamber; transferring the one or more workpieces through the secondtransfer port to the deposition chamber; coating the one or moreworkpieces in the deposition chamber; opening a third transfer portbetween the deposition chamber and the cooldown chamber; transferringthe one or more workpieces through the third transfer port to thecooldown chamber; cooling the one or more workpieces in the cooldownchamber; opening a fourth transfer port between the cooldown chamber andthe outlet chamber; transferring the one or more workpieces through thefourth transfer port to the outlet chamber; opening an outlet port ofthe outlet chamber; and removing the one or more of the workpieces fromthe outlet chamber through its outlet port.

A further embodiment may additionally and/or alternatively include:after the removing, closing the outlet port and pumping down the outletchamber.

A further embodiment may additionally and/or alternatively include: thetransferring to the deposition chamber leaving some of the workpieces inthe preheat chamber.

A further embodiment may additionally and/or alternatively include theworkpieces being held by a plurality of part holders, each having: afirst feature; and a second feature. At least one of said transferringscomprises a transfer mechanism engaging the second feature to shift thepart holder and install or remove the first feature from a complementaryfeature.

A further embodiment may additionally and/or alternatively include: thefirst engagement feature comprising a tapered feature tapering toward aproximal end. The second engagement feature comprises a channel and thecomplementary feature comprises a receptacle interior.

A further embodiment may additionally and/or alternatively include thepart holders each having an axis. The channel is open radially outwardfrom the axis and the tapered feature is centered along the axis.

A further embodiment may additionally and/or alternatively include thefirst feature being complementary to an engagement feature of aworkpiece handler of the deposition chamber. The transfer mechanism ispositioned in the first chamber to reach into an adjacent chamber duringthe associated said transferring.

A further embodiment may additionally and/or alternatively include amethod for using the deposition apparatus to coat a plurality ofworkpieces. The method comprises: sequentially passing workpiecesthrough the apparatus; and preheating a workpiece in the preheat chamberduring the sequential coating of at least first and second priorworkpieces in the deposition chamber.

A further embodiment may additionally and/or alternatively include theworkpieces passing through the apparatus while held by workpiece holdersthat pass with the workpieces.

A further embodiment may additionally and/or alternatively include theworkpiece being incrementally moved within the preheat chamber inconjunction with the sequential coating of the first and second priorworkpieces.

Another aspect of the disclosure involves a workpiece holder for adeposition apparatus. The workpiece holder comprises: a first featurefor holding the workpiece holder during deposition; and a second featurefor engagement by a transfer mechanism for transferring the workpieceholder.

A further embodiment may additionally and/or alternatively include thefirst engagement feature comprising a tapered feature tapering toward aproximal end and/or the second engagement feature comprising a channel.

A further embodiment may additionally and/or alternatively include theworkpiece holder comprising a nitride-coated metallic substrate.

A further embodiment may additionally and/or alternatively include theworkpiece holder being in combination with a workpiece held by theworkpiece holder wherein the workpiece comprises a gas turbine enginecomponent.

Another aspect of the disclosure involves a part manipulator for adeposition system. The part manipulator comprises: a proximal sectionrotatable about a first axis and translatable along said first axis; afirst intermediate section coupled to the proximal section by a firstjoint and extending radially outward from the first axis; a secondintermediate section coupled to the first intermediate section by asecond joint and rotatable relative to the first intermediate sectionabout a second axis parallel to and offset from the first axis; and areceptacle coupled to the second intermediate section by a third jointand rotatable relative to the second intermediate section about a thirdaxis transverse to the second axis.

A further embodiment may additionally and/or alternatively include oneor more of: the proximal section comprising a coaxial tri-shaft; thethird axis being orthogonal to and intersecting the second axis; and thereceptacle being coupled to the second intermediate section for endlessrotation about the third axis.

A further embodiment may additionally and/or alternatively include: afirst actuator coupled to drive said rotation about said first axis; asecond actuator coupled to drive said rotation about said second axis; athird actuator coupled to drive said rotation about said third axis; anda fourth actuator coupled to drive said translation along said firstaxis.

Another aspect of the disclosure involves a method for using adeposition apparatus to coat a plurality of workpieces. The methodcomprises: sequentially passing workpieces through the apparatus; andpreheating a workpiece in a preheat chamber during the sequentialcoating of at least first and second prior workpieces in the depositionchamber.

A further embodiment may additionally and/or alternatively include theworkpieces passing through the apparatus while held by workpiece holdersthat pass with the workpieces.

A further embodiment may additionally and/or alternatively include theworkpiece being incrementally moved within the preheat chamber inconjunction with the sequential coating of the first and second priorworkpieces.

A further embodiment may additionally and/or alternatively include theworkpieces being gas turbine engine components and the coating being ofa ceramic coating.

A further embodiment may additionally and/or alternatively include theworkpieces being in the preheat chamber for at least 130% of a time theyare in the deposition chamber.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially schematic top view of a deposition system.

FIG. 1A is an enlarged view of a deposition chamber of view of thesystem of FIG. 1.

FIG. 2 is a partial vertical cutaway view of the system of FIG. 1, takenapproximately along line 2-2.

FIG. 3 is a partial vertical cutaway view of the system of FIG. 1, takenapproximately along line 3-3.

FIG. 4 is a partially schematic view of a fixtured workpiece.

FIG. 5 is a partially schematic top view of an alternative depositionsystem.

FIG. 6 is a partially schematic top view of another alternativedeposition system.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 shows a deposition system 20 for depositing coating on workpieces22 in the interior 24 of a deposition or coating chamber 26. The systempasses the workpieces downstream along a workpiece flowpath passingsequentially through a first load lock chamber 28 forming an infeedchamber and having an interior 29, a preheat chamber 30 having aninterior 31, the deposition chamber 26, a cooldown chamber 34 having aninterior 35, and a second load lock 38 forming an outlet chamber andhaving an interior 39.

In an alternate embodiment (not shown), there is no cooldown chamber 34.In this alternate embodiment, the system passes the workpiecesdownstream along a workpiece flowpath passing sequentially through afirst load lock chamber 28 forming an infeed chamber and having aninterior 29, a preheat chamber 30 having an interior 31, the depositionchamber 26, and a second load lock 38 forming an outlet chamber andhaving an interior 39.

In another alternate embodiment (not shown), there is no second loadlock 38. In this alternate embodiment, the system passes the workpiecesdownstream along a workpiece flowpath passing sequentially through afirst load lock chamber 28 forming an infeed chamber and having aninterior 29, a preheat chamber 30 having an interior 31, the depositionchamber 26, and a cooldown chamber 34, which also acts as an outletchamber, having an interior 35.

As is discussed further below, workpieces are carried through the systemon part holders (fixtures) 44. Depending upon implementation, anindividual fixture may hold a single workpiece or multiple workpieces.In the deposition chamber, the workpieces may be manipulated by means46. An exemplary means is a sting mechanism discussed below.

In this example, a loading station (loader) 50 and an unloading station(unloader) 52 are schematically illustrated. These may be robots (e.g.,six-axis industrial robots) to transfer fixtured workpieces from and toconveyors, pallets, and the like (not shown).

In operation, the deposition chamber operates at a high speed so thatworkpieces can be coated in less time than the required pre-heat timeand cooldown time. For example, to coat a single part holder'sworkpiece(s), the chamber may require a time of T_(D). The required ordesired preheat time T_(PH) may be an exemplary at least 130% of T_(D)(e.g., at least 150% or at least 200% such as an exemplary 130%-500% or150%-500%). An upper end on preheat time is not similarly limited. Oncethe part has reached temperature it may stay there for a reasonable timewithout affecting subsequent processing. Clearly, times on the order oftens to hundreds or more of T_(D), or on the order of tens to hundredsor more of the minimum T_(PH), may begin to detract from part life.However, economics suggests that anything more than needed to reachtarget temperature is an unnecessary loss to be minimized. Similarly,the required or desired cooldown time T_(CD) may be an exemplary 50% ofT_(D) (e.g., 50%-300%). Cooldown time is less important than preheattime and influenced by different factors. Preheat time is determined bythe desired preheat temperature/uniformity. Cooldown may be moreinfluenced by handling considerations. Once coated, environmentalconditions during cooldown may be less relevant than those duringpre-heat.

To accommodate different required times in each of the chambers, thepreheat chamber and cooldown chamber may each have multiple stationsallowing them to contain multiple part holders and thus serve asbuffers. The part holders may thus spend more time in the preheatchamber and the cooldown chamber than in the deposition chamber. Thus agiven part holder will be in the preheat chamber or cooldown chamberduring at least two cycles of other part holders being processed by thedeposition chamber.

In this example, the buffer systems 60 each comprise a carousel system61 (FIG. 2) (e.g., a track, belt (e.g., on rollers), or linked apparatusforming a circuit). The buffer system has a number of locations 62 forholding workpieces. In the carousel example, these are occupied byreceptacles 64. The system 60 has an actuator 66 (e.g., a stepper orother motor with appropriate gearing, drive chains and belts, and/or thelike) for driving the carousel to circulate the receptacles along acircuit (e.g., shown as a racetrack or obround layout) through aplurality of locations. These plurality of locations comprise: areceiving location 62-1 for receiving a workpiece (inclusive of aplurality of co-fixtured workpieces); and a discharging location 62-2for discharging the workpiece. In this example, there are one or morefurther locations 62-3 for buffering workpieces. Discussed furtherbelow, the receptacles have a feature (e.g., a compartment) 70 (FIG. 2)complementary to a feature of the part holder 44. FIG. 2 schematicallyshows that a pair of heating elements 76 may be alongside opposite sidesof a flowpath leg of the workpieces through the preheat chamber toshield the carousel from the heating elements above. Similarly, a pairof thermal shields 78 may be along opposite sides of the flowpath (e.g.,defining a narrow slot between for a shaft of a parts holder to pass).Such heating means may be eliminated from the cooldown chamber.

In this example, the inlet chamber has an inlet port 80 and the outletchamber has an outlet port 82. These may be closeable via appropriategate valves or other doors 84, 86. Between chambers, there will be oneor more ports or doors. For example, a single door may be locatedbetween adjacent chambers and may be formed by gate valve assembliesschematically identified as 90, 92, 94, and 96 defining ports 98, 100,102, 104 between chambers.

The system also includes means for transferring the fixtured workpiecesto and from the buffer systems. FIG. 1 shows means: 120 for transferringworkpieces from the chamber 28 (e.g., a receptacle 121 in the chamber28) to the chamber 30; 122 for transferring workpieces from the chamber34 to the chamber 38 (e.g., a receptacle 123 in chamber 38); 124 fortransferring workpieces from the chamber 30 to the chamber 26; and 126for transferring workpieces from the chamber 26 to the chamber 34. Themeans may be general purpose robots (e.g., six axis industrial robotsoptionally with a specialized end effector or with a generic gripper endeffector) or may be specialized transfer mechanisms. As is discussedfurther below, each exemplary means is based on existing industrial toolchanger technology. An exemplary tool changer technology is found inU.S. Pat. No. 6,641,511 of Patel et al., issued Nov. 4, 2003, andentitled “Movable arm activated tool changer for machine tool system.”Such tool changer technology uses tool holders having a feature formounting in the tool chuck (when in use) and in a magazine of a rotarychanger (when not in use). The tool holder has another feature forengagement by some form of transfer mechanism for transferring the toolholder between the chuck and magazine.

Each exemplary transfer means or mechanism comprises an arm 130 (FIG.1A) having a distal end feature 132 for engaging the workpieces (ortheir fixtures in this example). A proximal end 134 is coupled to one ormore actuators 136, 138 (FIG. 2) for actuating the arm to move thefeature between a plurality of positions. The exemplary actuator 136 isa rotary actuator for rotating the arm 130 about an associated axis 502(FIG. 1A). An exemplary actuator 138 (FIG. 2) is a linear actuator fortranslating the arm parallel to the axis 502. Rotationally, an exemplarythree positions or conditions are shown in FIG. 1A: a solid lineretracted/disengaged/idle condition where the means (e.g., the arm 130)does not block the associated port or interfere with the associatedcarousel or means 46 (deposition chamber sting mechanism); acarousel-transferring position/condition (shown as 130′) fortransferring a fixtured workpiece to or from the associated carousel;and a position/condition (shown as 130″) for transferring to or from theassociated load lock or the deposition chamber. With the exemplarytransfer means located in the chambers 30 and 34, this lastposition/condition involves the transfer means reaching through theassociated port. Translationally, the three conditions may also have oneor more associated positions. For example, each may have a loweredcondition/position corresponding to a workpiece (or its fixture) fullyseated in an associated receptacle. A raised position may have theworkpiece or fixture disengaged from such receptacle (allowing lateralmovement by rotation about the axis 502).

When discussing such transfer means, the transfer means transferringworkpieces into the subject chamber may be referred to as an infeedtransfer means while the transfer means transferring workpieces out ofsuch subject chamber may be referred to as an outfeed transfer means.

The exemplary fixture 44 is shown in FIG. 4 as having two subsections orsubsystems: a section 300 (mounting section) for mounting and handling;and a section 302 (fixturing section) for engaging the workpiece(s) 22.The exemplary illustrated tool chamber mounts a single workpiece 22. Theexemplary workpiece 22 is shown as a vane having an airfoil 320 (e.g.,having a leading edge, a trailing edge, and a pressure side and asuction side extending between the leading and trailing edges). Theexemplary vane airfoil expands spanwise between an inboard or innerdiameter (ID) platform 322 and an outboard or outer diameter (OD) shroud324. The exemplary workpiece comprises a superalloy substrate (e.g., anickel-, cobalt-, and/or iron-based superalloy). The substrate may beara coating (e.g., prior to any coating applied in the apparatus). Forexample, the substrate may bear an MCrAlY bondcoat at least along keyportions to be coated such as the airfoil exterior and gaspath-facingsurfaces of the platform and shroud which are to be ceramic coated inthe apparatus 20. The exemplary section 302 is formed as a fixturingsection for holding the part. In the exemplary vane, the section 302comprises a first portion 330 having a pocket 332 for receiving one ofthe shroud and platform (e.g., the shroud as shown). In this example,the fixture includes a second portion 334 having a pocket 336 engagingthe other of the platform and shroud. Differently-configured fixturingsections would be appropriate for different components. A plurality ofstruts 338 connect the portions 330 and 334 to each other. In thisexample, the struts 338 hold the workpiece clamped between the portions330 and 334 and may have clamps, fasteners (e.g., screws) and/or othermeans for at least partial removability or releasability to allowinstallation of and removal of the workpiece 22.

This exemplary workpiece holder 44 makes the section 302 removable fromthe section 300. This may serve one or more purposes including allowingdifferential use rates of the two and allowing one configuration ofsection 300 to be used with multiple configurations of section 302corresponding to different configurations of workpieces to be coated.

To allow mating of the sections 300 and 302, these sections haveinterfitting features. Exemplary interfitting features comprise an endportion 340 of a shaft 342 of the section 302 received in a compartment344 of a collar 346 of the portion 300. As an exemplary means forreleasably locking the two together, a locking pin 348 may pass throughbores in both the shaft portion 340 and collar 346 and may have springdetent mechanism or other locking feature to lock the pin in place.Alternative fastener-based systems may also be used.

The exemplary section 300 has a section 360 for engagement by thereceptacles (e.g., the compartment 70, 251 of receptacles of the preheatchamber, the cooldown chamber, and/or the part manipulator of thedeposition chamber). A separate feature 362 may be provided to allowengagement by the transfer mechanism for transferring. The exemplarysection 360 comprises a feature such as a tapering portion 364 (taper).The exemplary tapering portion 364 tapers radially inward (relative toan axis 530) toward a proximal end 366 of the section 300. The exemplarytaper 364 comprises a frustoconical surface which may be received by acomplementary interior surface of said complementary receptacles(discussed further below). In addition to the taper 364, the exemplarysection 360 comprises a further feature 370 which may serve one or moreof several purposes including allowing locking or detenting of theworkpiece holder 44 in the associated receptacle and/or allowing aprecise axial positioning/registration of the workpiece holder in thereceptacle. The exemplary feature 370 comprises a spherical protrusionat the end 366. This may be received in a complementary portion of thereceptacle interior (e.g. having a detent mechanism to detent the holder44 in an installed condition).

The exemplary section 362 is formed as a channel structure. The channelstructure comprises a proximal flange 380, a distal flange 382, and areduced diameter portion/area 384 therebetween. The outer diameter (OD)surface along the reduced diameter portion 384 and the adjacent faces ofthe flanges form a respective base and sidewalls of an annular channelabout the axis 530. This allows a fork or other end effector 130 (FIG.1A) of the transfer mechanism to engage the workpiece holder. Forexample, the arm 130 or fork may have parallel faces spaced apart by thewidth of the channel or slightly less than such width and may have asemi-circular or nearly semi-circular lateral recess 132 complementaryto the portion 384. Such an end effector may approach the tool holderlaterally with the channel 362 receiving adjacent faces of the endeffector and the recess 132 receiving the reduced diameter portion 384.Translation of the end effector parallel to the axis 530 may remove theworkpiece holder from the receptacle (e.g., via overcoming detent forceon the feature 370). A reverse motion of the end effector parallel tothe axis 530 (and axis 502) may install/seat the workpiece holder 44 inthe receptacle, again overcoming detent force (if any) on the feature370.

The exemplary deposition chamber 26 is configured for electron beamphysical vapor deposition (EB-PVD). In this example, at least oneelectron beam (EB) gun 420 (FIG. 1) is positioned to direct its beam toone or more deposition material sources 422, 424 (FIG. 1). In thisexample, there are two distinct sources 422, 424 (ingots) of differentmaterials. For example, there may be ceramics of different compositionfor forming distinct layers in a thermal barrier coating, erosioncoating, abradable coating, or abrasive coating. For example, both maybe zirconia-based such as having one being a yttria-stabilized zirconia(YSZ) such as 7YSZ and the other being a gadolinia-stabilized zirconiaor a YSZ of different yttria content or other dopant. As is discussedfurther below, a part manipulator 46 may be used to position theworkpiece(s) in two distinct positions or sets of positions associatedwith deposition from the two distinct sources (e.g., generally above therespective ingots so as to be approximately centrally positioned in theresulting vapor plume).

Other routine EB-PVD features are not shown but may be present. Forexample one or more vacuum pumps are coupled to each of the chamberswith valves, pressure sensors, etc. to independently control pressure inthe chambers. The deposition chamber will also be connected to processgas sources (e.g., cylinder banks of Ar, O₂, N₂, and/or He) byassociated valves, etc. Various other sensors may be used to detectatmospheric compositions in the chambers and deposition parameters. Anychamber directly connected to the deposition chamber may also beconnected to such gas sources to avoid contaminating the depositionchamber when the two are open to each other. Any chamber serving as aload lock may also have a gas source such as a dry air source (e.g.,filtered/dehumidified factory air) used to pressurize the chamber priorto opening for loading or unloading. This, plus maintenance of gas flowwhile such chamber is open to the factory ambient conditions mayprevent/limit infiltration of moist factory air into the system.

In the exemplary implementation, a single electron beam gun 420 ispositioned to be able to raster both ingots and may be coupled to acontrol system (controller 400 (FIG. 1)) to sequentially heat the twosources for the two stages of deposition (or more stages if more thantwo layers are involved). With the exemplary deposition chamber, boththe preheat chamber 30 and the cooldown chamber 34 are along a firstside 430 of the deposition chamber. The deposition chamber has a secondside 432 opposite the first side and third and fourth sides 434, 436transverse thereto. The chamber also has a bottom or lower side 438(FIG. 3) and a top or upper side 440. The exemplary EB gun 420 ispositioned centrally along a junction of the top 440 and second side 432so as to diagonally point downward toward the bottom of the chamber.More particularly, the electron beam gun points diagonally downwardtoward a thermal tray 444 containing a ceramic media and surrounding apair of associated crucibles 446 (e.g., via an ingot loader extendingupward through a port in the bottom 438).

For manipulating the workpieces in the deposition chamber, a partmanipulator 46 (FIG. 1A) is used. The exemplary manipulator is a stingand rake arm system. The exemplary sting and rake arm system has atri-axial sting shaft 222 penetrating a seal 224 in the wall 434. Thetri-axial sting shaft has three shafts (at least two of which aretubular) concentrically about an axis 550. Actuators (e.g., drivemotors) 226, 228, 230 (FIG. 1) drive respective rotations of the threeshafts and a further actuator 232 drives translation of the sting andrake arm parallel to the axis 550 (FIG. 1A). In the general, the conceptof coaxial and tri-axial shafts is known. However, the particularorientation of components as discussed below is not believed known.Accordingly, the overall layout is illustrated and discussedschematically with the omission of internal bevel drive gears, etc. asthese manufacture details would be within the skill of one of ordinaryskill in the art when presented with this schematic layout.

Returning to FIG. 1, actuation by one of the actuators (e.g., 226) mayrotate the sting and rake arm assembly in at least a range of motionabout the axis 550. As is discussed below, this degree of freedom mayhelp optimize workpiece orientation during deposition and may help bringthe workpieces into and out of a transfer condition (e.g., an uprightorientation) for transfer to and from the preheat chamber or cooldownchamber. Translation by the actuator 232 may, again, be used both toposition the workpieces for transfer to the preheat chamber or cooldownchamber (in this example, transfer from the preheat chamber being in arelatively contracted condition of the sting and transfer to thecooldown chamber being in a relatively extended condition). However,this translation parallel to axis 550 may also place the workpieces inposition aligned with the respective sources 422 and 424 (againrespectively being in relatively contracted versus extended conditions).

The rake arm comprises a radial link or arm 240 (FIG. 1A) extendingradially outward (relative to the axis 550) from a proximal end at ajoint 242 with the sting shaft assembly 222. At a distal end of the arm240, a joint 244 connects to a proximal end of an arm 246 having an axis552 parallel to the axis 550. The arm 246 extends to a distal end at ajoint 248 with a part-holding receptacle 250. The receptacle 250 has anaxis 554 transverse to the axis 552. The joints 244 and 248 providerespective relative rotation about the axes 552 and 554 driven by theremaining actuators 228 and 230, respectively (e.g., via the bevel gearsystems discussed above). The exemplary rotation about the axis 552 isused in conjunction with the rotation about the axis 550 to orient theworkpiece relative to such axes. Again, this may be used to move betweentransfer conditions/positions and coating conditions/positions.

Exemplary materials for the components of the part manipulation systemthat have less exposure to heat in the coating chamber (222, 242, and240 in FIG. 1A, and the internal triaxial shafts, not shown) includestainless steels such as 304, 316, and 316L stainless steel. Exemplarymaterials for the components of the part manipulation system that havemore exposure to heat (e.g., 244, 246, and for the bevel gears (notshown) and the part holder receptacle 250 and part holder 44), includenickel-based superalloys such as Inconel 718. Section 302 of the partholder 44 can alternatively be fabricated out of stainless steels suchas 304 or 316 stainless. The outer tubes of the part manipulation systemcan be fabricated by welding of tubing sections with either round orsquare cross sections. The bevel gear housings of joints 244 and 248 canbe fabricated from machined cast IN718 preforms.

In an alternative embodiment (not shown), at least one portion of thepart manipulation system 46 is protected from radiative heat flux usingheat shields. This may include shielding of the receptacle and/or partholders. These heat shields may consist of at least one layer of sheetmetal (typically stainless steel) or nickel-based alloys. These heatshields are attached to outer surfaces of at least one component of thepart manipulation system, typically using a clamshell-type design heldtogether with safety-wired bolts.

In another alternative embodiment (not shown), at least one portion ofthe part manipulation system 46 is water cooled to minimize distortionby the heat in the coating chamber. The sections of the partmanipulation system that would be water cooled would have a coppertubing circuit brazed to the outer surface of the component. Thecomponent and water cooling surface would then be protected from thecoating environment using a sheet metal shroud consisting of at leastone layer of sheet metal, comprised of stainless steel or nickel-basedalloys. The sheet metal shrouds would optionally not be used around thebevel gear housings of joints 244 and 248, nor the part holderreceptacle, 250, because the housings themselves would protect thecopper tubing. The inlet and outlet water plumbing to the copper tubingcircuit would be routed through the innermost of the triaxial shafts,and would consist of copper tubing.

In this example, the transfer positions have the receptacle 250 facingupward. The receptacle 250 has a compartment 251 complementary to theworkpiece holder as is discussed above. In the transferconditions/positions, the workpiece holder extends upward from thereceptacle. In such transfer conditions, the receptacle may be at evenheight with the advent terminal receptacle of the associated preheatchamber or cooldown chamber or at least within the vertical range ofmotion of the associated transfer mechanism. For deposition, rotationabout the axis 552 and/or 550 may bring the part downward into closerproximity with the sources or the motion about axis 550 may pitch thepart about the axis to change the angle of axis 554 relative the floor438 but without bringing the part closer to the sources. Duringdeposition, rotation about the axis 554 may help provide evenness ofpart coating. For example, this rotation may be a continuous rotationduring deposition (e.g., at exemplary speeds of up to 300 rpm (e.g.,more particularly, 100-200 rpm or 100-300 rpm, in a relatively fastdeposition process). The movements about the axes 550 and 552 may haverestricted/limited ranges of motion. For example, exemplary ranges ofmotion for each are 90°.

In the exemplary tri-axial sting shaft configuration, the rotation aboutthe axis 554 is driven by the center shaft, rotation about the axis 550driven by the outer shafts, and rotation about the axis 552 driven bythe intermediate shaft. The exemplary actuator 232 may be a linearactuator such as a stepper motor engaging a rack and pinion or may be alinear motor.

Various surfaces which may be in the deposition chamber or otherwiseexposed to deposition materials may bear protective coatings. Onefunction of the coatings is to prevent sticking of coating material.Exemplary coatings are nitride coatings (e.g., TiN or TiAlN) disclosedin U.S. Pat. No. 8,603,582 of Bernaski et al., issued Dec. 10, 2013, andentitled “Non-stick masking fixtures and methods of preparing same”, thedisclosure of which is incorporated by reference in its entirety hereinas if set forth at length.

For example, all or some of the surfaces of the part holder 44 and/orreceptacle 250 may be coated reduce adhesion of any stray ceramiccoating that reaches these surfaces during ceramic coating in thedeposition chamber. Such coatings may enable easy cleaning of thosesurfaces. The coatings may also reduce friction and stiction duringremoval of the part holder from the receptacle 250. It similarly mayreduce friction between mating surfaces of the partholder sections 300and 302. It similarly may reduce friction between individual movableparts of those sections such as clamps and fasteners used to hold thepart.

Thus, the same coating that acts as a non-stick coating along exposedareas of the part holder (or other component) may act as ananti-friction coating for mating surfaces of the part holder and/orreceptacle (e.g., section 360 and receptacle compartment 251 (or 250)).In an exemplary coating process, the surfaces to be coated with TiN orTiAlN may be prepared for that coating by polishing (e.g., to a surfaceroughness of 25 Ra or lower) for strong adhesion of the TiN or TiANcoating. The coating may be applied to the surfaces by physical vapordeposition or chemical vapor deposition. Alternatively, the coating maybe applied to the part by plating followed by nitriding.

Exemplary coating thickness is at least 1 micrometer or at least 2micrometers or in a range of 1-10 micrometers, more particularly, 1-5micrometers, 2-5 micrometers or 3-5 micrometers (e.g., measured as amean, median, modal, or local thickness). Exemplary coatings are alongmajorities of the exposed areas of the partholder and along a majorityof partholder surface area of contact zones between its pieces andbetween it and the receptacle.

An exemplary part movement sequence is described in a system having fourlocations/positions along the part flowpath in the preheat chamberrather than the illustrated three. In this example, cycle time for thedeposition chamber is 5 minutes. Use of four positions in the preheatchamber for heating allows the parts to spend up to approximately 20total minutes in the preheat chamber. A sequence of parts is referred toas “Part 1” et seq. In continuous operation, there will be a queue ofparts along the part flowpath in the apparatus ahead of Part 1.

In the exemplary embodiment only a nominal 15 minutes is spent in thepreheat chamber. The heating elements are partially clear of the firstand fourth positions (e.g., adjacent only the side that is not in theway of the approach of the transfer apparatus) to allow access by theassociated transfer apparatus. Thus little heating would occur in thefirst position. Accordingly, during most of the 5 minute system cycle apart is not in the first position.

The process sequence is started by opening door 84. Via loader 50 (ormanually), Part 1 is loaded into load lock chamber 28's receptaclethrough port 80. Door 84 is then closed and the vacuum line valve (notshown) is opened to pump down the chamber interior 29 to achieve lowvacuum operating (LVO) pressure (e.g., less than 30 Pa, moreparticularly 1.0-20 Pa or 5-20 Pa or 5-15 Pa or 10-15 Pa).

Gate valve 90 is then opened and the transfer mechanism 120 is used toengage part holder feature 362 (FIG. 4) for Part 1 and to move theholder 44 with that part into racetrack position 1 (e.g., 62-1 in FIG.2). Gate valve 90 is then closed and the preheat chamber may optionallybe pumped further down below LVO pressure or to establish a relativelyinert atmosphere (e.g., by flowing argon or nitrogen from a supply (notshown) maintained at pressure via cooperation with a vacuum pump (notshown)).

Load lock chamber 28 vacuum line is then closed and the load lock ispressurized (e.g., with air from an air source to atmospheric pressure)to load Part 2.

Because, at the startup of the machine, no parts are in positions aheadof Part 1 in the preheater, immediately after Part 1 is transferred toposition 1, the conveyor is actuated (e.g., via actuator 66) to movePart 1 to racetrack position 2 (e.g. the first of two intermediatepositions). This step may occur while the load lock is being pressurizedor even before.

Part 1 is then held at position 2 for an interval (e.g., the remainderof the 5 minute cycles to start pre-heat). The sequence is then repeatedwith further parts until part 1 is at racetrack position 4 (62-2), part2 is at position 3 (the second of two positions 62-3), part 3 is atposition 2, and part 4 has just been loaded into position 1. At thispoint, gate valve 90 has just been closed. However, at this point, theracetrack can't be indexed until part 1 is removed.

During this loading of the buffer in the preheat chamber, evaporation isstarted in the coating chamber, by using the electron beam to melt ingot422, and the process is brought to steady-state, prior to transfer ofPart 1 from the preheat chamber to the deposition chamber.

At this point in the startup sequence, Part 1 has experiencedsubstantial ramp-up heating for two five minute intervals in positions 2and 3 and a stabilization in position 4 for a 5 minute interval. Part 1is thus fully preheated and ready for transfer to the depositionchamber.

A shutter (not shown) may be shifted (e.g., lowered) between positions 3and 4 (e.g., the last two positions along the delivery flowpath) toshield the heating elements around positions 1, 2 and 3 fromcontamination by any residual deposition material vapor when Part 1 istransferred to the deposition chamber.

In another embodiment (not shown), a gate valve (in place of the shutterdiscussed in the above paragraph) is lowered between positions 3 and 4.Then the pressure in the volume surrounding Part 1 in position 4 isequalized by closing the vacuum line (not shown) and flowing inertprocess gases such as N₂ and Ar prior to the next step (describedbelow). This latter embodiment enables maintaining positions 1, 2, and 3in the preheat chamber at higher vacuum levels (lower pressures),avoiding nonoptimal oxidation.

Part 1 is transferred from position 4 in the preheat chamber to thetriaxial manipulator in the coating chamber as follows. Feature 362 ofthe Part 1 part holder is engaged with transfer mechanism 124. At thesame time, the rake arm part receptacle 250 is moved to a position alongthe arc of mechanism 124 in order to receive the part holder. The rakearm receptacle 250 is oriented such that its longitudinal axis 554 isvertical in the chamber by rotating about axis 552.

Gate valve 94 is opened and the holder holding Part 1 is moved over therake arm receptacle 250 using the transfer mechanism 124. Part 1 is thenlowered into the rake arm receptacle 250. The part holder may seat witha detent action, or a solenoid or other non-detent latching mechanism(not shown) may be used to lock the holder in place. Such a latchingmechanism may be desirable because the rake arm manipulations of thepart holder may involve inertial forces that would overcome a detentaction commensurate with the strength of the transfer mechanism.

The transfer mechanism 124 is then retracted. Gate valve 94 is thenclosed, and the shutter, if any, retracted/raised. For the alternativeembodiment that uses a gate valve instead of a shutter, the vacuum lineis then opened to pump the volume around position 4 in the preheaterdown to the desired high vacuum level.

The racetrack is then indexed using the actuator 66 to move Part 2 toposition 4, Part 3 to position 3, and Part 4 to position 2. Part 5 isthen loaded into position 1 (similarly to how the other parts were soloaded). Alternatively, Part 5 may be loaded late in that 5-minutecycle. This completes the startup sequence for filling the buffer in thepreheater. The process described above is repeated to maintainsteady-state operation.

After gate valve 94 is closed after the transfer of Part 1, rotation ofPart 1 around axis 554 is started immediately and the rake arm isrotated around axis 552 to bring axis 554 parallel to the melt pool oningot 422. The part is then tilted as per a duty cycle by rotatingaround axis 550 between angles −A and +B, where A and B vary from 0 to45 degrees, depending on the geometry of the part. This tilting occursat the same time of the rotation of Part 1 around the axis 554, toensure uniformity. The rate of rotation about axis 554 and tilting aboutaxis 550 may not be constant, and rotation and tilting may be stoppedfor dwells at regular intervals. Tilting rates vary from 0.5 to 20degrees per second, and dwell times vary from 0 to 20 seconds. Anexemplary amount of time to coat the first layer using ceramic ingotsource 422 is 1 minute. An exemplary composition for the first layer is7YSZ.

Next, the EB gun raster pattern is moved from source 422 to source 424to melt and evaporate ingot source 424, simultaneously freezing ingotsource 422. Simultaneously or shortly before or after switchingrastering, the actuator 232 is used to move the part over ingot source424. An exemplary amount of time to coat the second layer using ceramicingot source 424 is 4 minutes. An exemplary composition for the firstlayer is a gadolinia stabilized zirconia (GSZ) (e.g., 59 wt. % gadoliniastabilized zirconia). Other times and other combinations of layering maybe involved. The total time may be up to essentially equal the partcycle time.

At all times, the cooldown chamber 34 is maintained at LVO pressureusing process gas flowmeters in a feedback loop with a vacuum pump(neither shown). At the end of the coating cycle for Part 1, the rakearm is rotated to bring the part and part holder back up to the verticalposition by rotating around axis 552. The manipulator 240 simultaneouslytranslates into a transfer position along the arc of transfer mechanism126. Gate valve 104 is then opened, transfer mechanism 126 engagesfeature 362 of the Part 1 part holder, then the rake arm solenoid (notshown) releases ball 370 and the part is moved into the cooldown chamberfirst position. Gate valve 104 is then closed and the rake arm is movedback to the position to receive Part 2 from the preheat chamber and thecycle of feeding the deposition chamber continues.

Part 1 is then moved through the cooldown chamber as parts complete thecoating cycle and are moved in behind Part 1. Before Part 1 reaches thefinal position in the cooldown chamber, the outlet loadlock chamber 38is pumped down to the same LVO pressure as the cooldown chamber. WhenPart 1 reaches the final position in the cooldown chamber, gate valve100 is opened and mechanism 122 is used to transfer the part to theoutlet load lock chamber. Gate valve 100 is then closed, and the outletloadlock chamber 38 is vented to bring the pressure up to atmosphericpressure. Door 86 is opened and the part is then unloaded using unloader52, or manually.

In an alternative embodiment (not shown), no cooldown chamber is used,and the part is moved directly from the coating chamber to the loadlock.The part is then quenched using flowing gas such as Ar, N₂, He, or air,with the vacuum line for the outlet load lock (not shown) closed,allowing the chamber to come up to atmospheric pressure. Door 86 isopened, then the part is then removed from the loadlock using 52 ormanually, allowing sufficient time to pump down to LVO pressures toreceive the next part coming out of the coating chamber.

FIG. 5 shows a system 600 that implements a number of differencesrelative to the system 20 of FIG. 1. Various of these differences may beimplemented individually or in other combinations.

The first variation is that the buffer system 60-1 carousel 61-1 issimply a single-axis 560 carousel having a circular array of even-spacedreceptacles. In this regard, it also reflects a second variation in thatthe receptacles remain upright throughout (contrasted with the FIG. 1embodiment rotating the receptacles about a transverse axis to have areturn leg inverted). A further variation is that a single chamber 30-1serves functions of both the preheat chamber and cooldown chamber. Theheater 76 is localized to one side of the chamber for preheating; theopposite side serves as a return path for cooldown. Similarly, a singleload lock chamber 28-1 is used for both inlet/infeed and outlet/outfeedpurposes. A single loader/unloader mechanism (not shown) may service theload lock or two respective separate mechanisms may service the loadlock as in FIG. 1. Again, one or both of these mechanisms may bereplaced with manual handling.

FIG. 6 shows a system 602 having a buffer system 60-2 as furthervariation of the system of FIG. 5 wherein the transfer mechanisms 120-1,124-1 each comprise two opposed arms 130-1 and 130-2. The exemplary armsmay be formed as an integral unit (e.g., as opposite halves of a singlepiece on opposite sides of the axis of rotation 502). Each exemplary armhas a feature 132. Each exemplary feature 132 of the given transfermechanism faces in the same circumferential direction (e.g., as an openchannel or recess is open toward the same circumferential direction).This allows one rotation of the transfer mechanism to bring one arm intoengagement with a tool holder in one of the carousel 61-2 receptacles inan associated location 62-1-1, 62-2-1 and the other into engagement witha tool holder in either the load lock 28-1 or the deposition chamber26-1. A single translation along the axis 502 may serve to disengageboth tool holders from the association receptacle. This may be followedby rotation about the axis 502 so as to exchange the locations of thetwo part holders. In yet alternative versions, however, such two-armedtransfer mechanisms may be used in methods wherein only one of the twoarms is engaging a tool holder at a given time.

Whereas, the FIG. 5 transfer mechanism axes 502 are off-center adjacentone vertical edge of the associated port through which they pass toolholders, the exemplary axes 502 are along the central verticallongitudinal centerplane in the FIG. 6 embodiment. This may require thatthe FIG. 6 embodiment have relatively wider ports 98-1, 102-1 than theFIG. 5 embodiment or the FIG. 1 embodiment. Additionally, the use of asingle combined preheat and cooldown chamber with the exemplary FIG. 5or FIG. 6 transfer mechanisms means that the sting arm loading andunloading positions can be coincident.

In this example, there is an even number of receptacles evenlycircumferentially spaced about the carousel. With the FIG. 6 embodiment,an exemplary cycle is illustrated starting just after a part exchangehas occurred with the deposition chamber. In this situation, at thispoint time, coated parts occupy both transfer positions 62-1-1, 62-2-1and all the intermediate positions along the unloading flowpath (in thecooldown zone 622); uncoated parts occupying the intermediate locationsin the preheating zone 620 adjacent the heating elements. An uncoatedpart is also in the load lock receptacle. The load lock has been pumpeddown to the pressure of the preheat/cooldown chamber. The valve 90-1 isthen opened to expose the load lock 28-1 interior 29-1 to the interior31-1 of the preheat/cooldown chamber 30-1. The transfer mechanism 120-1then rotates (e.g., 90° about the axis 502) from an illustrated neutralor retracted condition to a condition where its respective arms 130-1and 130-2 engage the receptacles in the adjacent transfer position62-1-1 of the chamber 30-1 and the transfer position of the load lock28-1. The arms are thereafter raised to disengage the part holders fromthe receptacles and then rotated 180° about the axis 502 to switch theparts between the associated chambers. Then the arms are verticallyretracted to seat the part holders in their new receptacles. The armsare then rotated out of engagement (e.g., by 90°) back to the retractedcondition.

The valve 90-1 may then be closed. Thereafter, and optionally coincidentwith the next movements discussed in the chamber 30-1, the vacuum of thechamber 28-1 may be broken, the door 84-1 opened, and then the coatedpart in the chamber 28-1 exchanged by the loader/unloader or separateloaders and unloaders for a fresh uncoated part. The process in thechamber 30-1 may be otherwise similar to that in the chamber 30. At somepoint in the cycle, the carousel 60-2 is indexed one position (e.g.,counter-clockwise in direction 562 about axis 560 as viewed from abovein the FIG. 6 example). This brings a heated workpiece into theoperative position 62-2-1 for transfer to the deposition chamber. Theexact timing of this indexing within the cycle may depend on a number offactors including the geometry of the heating elements. For example, ifthe heating elements do not provide adequate heat at location 62-2-1,this indexing may preferably occur late in the cycle. Whencoating/deposition is complete, the valve 94-1 is opened allowingcommunication through the port 102-1. The transfer mechanism 124-1 isthen used to exchange parts between the deposition chamber and thereceptacle in the location 62-2-1 in similar fashion to the exchangemade by the mechanism 120-1. The gate valve 94-1 may then be closed andboth the coating process in the deposition chamber and theabove-mentioned actuations in the chambers 30-1 and 28-1 may repeat.

In yet a further variation, the recirculating loop of a carousel isreplaced by a system wherein workpieces are moved between fixedreceptacles. In one example, two receptacles are present. Both transfermechanisms may access either receptacle. For example, with the rotarymechanisms already described and shown, the two receptacles may fall ontwo circular arcs: a first arc centered on the rotation axis of thefirst transfer mechanism; and a second arc centered on the axis of thesecond transfer mechanism. In a second such example, only one receptacleis at the intersection of the two arcs, but one or more additionalreceptacles are along the individual arcs. The infeed transfer mechanismmight move the workpieces sequentially amongst the receptacles along itsarc until the intersection receptacle. Thereafter, the outfeed transfermechanism would acquire the workpieces and sequentially move themamongst the receptacles along its arc. A third such example might add athird transfer mechanism with a plurality of receptacles along a path(e.g., the arc of the exemplary transfer mechanisms). Terminalreceptacles would be respectively accessible by the infeed and outfeedtransfer mechanisms.

The use of “first”, “second”, and the like in the following claims isfor differentiation within the claim only and does not necessarilyindicate relative or absolute importance or temporal order. Similarly,the identification in a claim of one element as “first” (or the like)does not preclude such “first” element from identifying an element thatis referred to as “second” (or the like) in another claim or in thedescription.

Where a measure is given in English units followed by a parentheticalcontaining SI or other units, the parenthetical's units are a conversionand should not imply a degree of precision not found in the Englishunits.

One or more embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made. For example, whenapplied to an existing baseline configuration, details of such baselinemay influence details of particular implementations. Accordingly, otherembodiments are within the scope of the following claims.

What is claimed is:
 1. A deposition apparatus comprising: an infeedchamber; a preheat chamber; a deposition chamber; and optionally atleast one of a cooldown chamber and an outlet chamber, wherein: at leasta first chamber of the preheat chamber and, if present, the cooldownchamber contains a buffer system for buffering workpieces respectivelypassing to or from the deposition chamber; and the deposition apparatusfurther comprises: a workpiece handler positioned to hold workpieces forcoating in the deposition chamber; a transfer mechanism positioned totransfer workpieces between at least two of the chambers; a plurality ofworkpiece holders, each having: a first engagement feature complementaryto an engagement feature of the workpiece handler; and a secondengagement feature complementary to an engagement feature of thetransfer mechanism.
 2. The deposition apparatus of claim 1 wherein: thedeposition apparatus includes said cooldown chamber and said outletchamber; and a workpiece flowpath enters the infeed chamber and proceedssequentially through the preheat chamber, the deposition chamber, thecooldown chamber, and then exits the outlet chamber.
 3. The depositionapparatus of claim 1 wherein: the preheat chamber is a combinedpreheat/cooldown chamber.
 4. The deposition apparatus of claim 1wherein: the buffer system comprises a conveyor having a plurality ofreceptacles.
 5. The deposition apparatus of claim 4 wherein: theconveyor is a continuous loop circuit.
 6. The deposition apparatus ofclaim 1 wherein a workpiece flowpath from said infeed chamber to saidoutlet chamber comprises: a first leg from the infeed chamber to thedeposition chamber; and a second leg from the deposition chamber to theoutlet chamber, parallel but opposite in direction to the first leg. 7.The deposition apparatus of claim 1 wherein the deposition chambercomprises: an electron beam gun; and an ingot.
 8. The depositionapparatus of claim 1 wherein: the deposition apparatus includes saidcooldown chamber; and the deposition chamber comprises a workpiecehandler having a range of motion including: a first condition forreceiving a workpiece transferred from the preheat chamber; and a secondcondition for handing off the workpiece for transfer to the cooldownchamber.
 9. The deposition apparatus of claim 8 wherein the workpiecehandler range of motion includes: one or more deposition conditionsaccessible via rotation about a first axis relative to the firstcondition and second condition.
 10. The deposition apparatus of claim 9wherein the one or more deposition conditions comprises: a firstdeposition condition for deposition from a first plume of a firstmaterial; and a second deposition condition for deposition from a secondplume of a second material, said second deposition characterized by ashift parallel to the first axis relative to the first depositioncondition.
 11. The deposition apparatus of claim 9 wherein the workpiecehandler range of motion between said first condition and said secondcondition comprises a translation parallel to the first axis.
 12. Thedeposition apparatus of claim 9 wherein the workpiece handler range ofmotion includes: a part continuous rotation degree of freedom about anaxis orthogonal to the first axis.
 13. The deposition apparatus of claim9 wherein: the rotation about the first axis reorients the workpiecerelative to the to the first condition and second condition.
 14. Thedeposition apparatus of claim 8 wherein the workpiece handler comprisesa sting.
 15. The deposition apparatus of claim 1 wherein: the firstengagement feature comprises a tapered feature tapering toward aproximal end; and the second engagement feature comprises a channel. 16.The deposition apparatus of claim 15 wherein: the workpiece holders eachhave an axis; the channel is open radially outward from the axis; andthe tapered feature is centered along the axis.
 17. The depositionapparatus of claim 15 wherein: each of the plurality of workpieceholders has a fixturing section for engaging a workpiece; and the secondengagement feature is between the fixturing section and the firstengagement feature.
 18. The deposition apparatus of claim 1 comprisingsaid outlet chamber and wherein the deposition chamber has four sidesand a workpiece flowpath from said infeed chamber to said outlet chambercomprises: a first leg from the infeed chamber to a first side of thefour sides of the deposition chamber; and a second leg from the firstside of the deposition chamber to the outlet chamber.
 19. A method forusing the deposition apparatus of claim 1 to coat a plurality ofworkpieces, the method comprising: opening an inlet port of the infeedchamber; inserting one or more of the workpieces to the infeed chamberthrough its inlet port; closing the infeed chamber inlet port; pumpingdown the infeed chamber; opening a first transfer port between theinfeed chamber and the preheat chamber; transferring the one or moreworkpieces through the first transfer port to the preheat chamber;heating the one or more workpieces in the preheat chamber; opening asecond transfer port between the preheat chamber and the depositionchamber; transferring the one or more workpieces through the secondtransfer port to the deposition chamber; coating the one or moreworkpieces in the deposition chamber; opening a third transfer portbetween the deposition chamber and the cooldown chamber; transferringthe one or more workpieces through the third transfer port to thecooldown chamber; cooling the one or more workpieces in the cooldownchamber; opening a fourth transfer port between the cooldown chamber andthe outlet chamber; transferring the one or more workpieces through thefourth transfer port to the outlet chamber; opening an outlet port ofthe outlet chamber; and removing the one or more of the workpieces fromthe outlet chamber through its outlet port.
 20. A method for using thedeposition apparatus of claim 1 to coat a plurality of workpieces, themethod comprising: sequentially passing workpieces through theapparatus; and preheating a workpiece in the preheat chamber during thesequential coating of at least first and second prior workpieces in thedeposition chamber.
 21. A deposition apparatus comprising: an infeedchamber; a preheat chamber; a deposition chamber; and optionally atleast one of a cooldown chamber and an outlet chamber, wherein: at leasta first chamber of the preheat chamber and, if present, the cooldownchamber contains a buffer system for buffering workpieces respectivelypassing to or from the deposition chamber; and the deposition apparatusfurther comprises: a workpiece handler positioned to hold workpieces forcoating in the deposition chamber; a transfer mechanism positioned totransfer workpieces to and from the deposition chamber; a plurality ofworkpiece holders, each having: a first feature complementary to anengagement feature of the workpiece handler; and a second featurecomplementary to an engagement feature of the transfer mechanism wherebythe workpieces may be transferred between the buffer system and theworkpiece handler via the transfer mechanism.